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    Subject[PATCH] Convert serial_core oopses to BUG_ON
    Hi,

    With reference to these two bugs:

    http://bugzilla.kernel.org/show_bug.cgi?id=5958
    http://bugzilla.kernel.org/show_bug.cgi?id=6131

    it seems that folk are under the impression that serial_core is
    responsible for these bugs. It isn't.

    Calling serial functions to flush buffers, or try to send more data
    after the port has been closed or hung up is a bug in the code doing
    the calling, not in the serial_core driver.

    Make this explicitly obvious by adding BUG_ON()'s.

    I don't particularly want to add these BUG_ON()'s since they have a
    performance impact, but it seems that they're necessary to convey
    sufficient understanding about where the bug lies. The Bluetooth
    problem has been around for _ages_ (longer than the entry in bugzilla)
    and no one seems the least bit interested in fixing the fscking thing.

    I can only hope that adding these BUG_ON()'s provides sufficient
    clarity to cause people to look elsewhere.

    diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
    --- a/drivers/serial/serial_core.c
    +++ b/drivers/serial/serial_core.c
    @@ -71,6 +71,11 @@ static void uart_change_pm(struct uart_s
    void uart_write_wakeup(struct uart_port *port)
    {
    struct uart_info *info = port->info;
    + /*
    + * This means you called this function _after_ the port was
    + * closed. No cookie for you.
    + */
    + BUG_ON(!info);
    tasklet_schedule(&info->tlet);
    }

    @@ -479,6 +484,12 @@ uart_write(struct tty_struct *tty, const
    unsigned long flags;
    int c, ret = 0;

    + /*
    + * This means you called this function _after_ the port was
    + * closed. No cookie for you.
    + */
    + BUG_ON(!state);
    +
    if (!circ->buf)
    return 0;

    @@ -521,6 +532,12 @@ static void uart_flush_buffer(struct tty
    struct uart_port *port = state->port;
    unsigned long flags;

    + /*
    + * This means you called this function _after_ the port was
    + * closed. No cookie for you.
    + */
    + BUG_ON(!state);
    +
    DPRINTK("uart_flush_buffer(%d) called\n", tty->index);

    spin_lock_irqsave(&port->lock, flags);
    --
    Russell King
    Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
    maintainer of: 2.6 Serial core
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